B.B. King is apologizing to fans for a concert two weeks ago that got him heckled and drew international attention for the poor reviews.  King's people say the 88-year-old blues legend was exhausted from a long bus ride and forgot to take his diabetes medication before the performance at the Peabody Opera House.  Fans who'd paid hundreds of dollars for tickets complained King only sang a handful of songs and spent much of the night rambling on.